Merge branch 'master' of ssh://bitbucket.org/czan/honours

1 files changed, 1170 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
new file mode 100644
index 0000000..1193e97
--- /dev/null
+++ b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -0,0 +1,1170 @@
+//===--- CGRecordLayoutBuilder.cpp - CGRecordLayout builder  ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Builder implementation for CGRecordLayout objects.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CGRecordLayout.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/AST/CXXInheritance.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/Frontend/CodeGenOptions.h"
+#include "CodeGenTypes.h"
+#include "CGCXXABI.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Type.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetData.h"
+using namespace clang;
+using namespace CodeGen;
+
+namespace {
+
+class CGRecordLayoutBuilder {
+public:
+  /// FieldTypes - Holds the LLVM types that the struct is created from.
+  /// 
+  SmallVector<llvm::Type *, 16> FieldTypes;
+
+  /// BaseSubobjectType - Holds the LLVM type for the non-virtual part
+  /// of the struct. For example, consider:
+  ///
+  /// struct A { int i; };
+  /// struct B { void *v; };
+  /// struct C : virtual A, B { };
+  ///
+  /// The LLVM type of C will be
+  /// %struct.C = type { i32 (...)**, %struct.A, i32, %struct.B }
+  ///
+  /// And the LLVM type of the non-virtual base struct will be
+  /// %struct.C.base = type { i32 (...)**, %struct.A, i32 }
+  ///
+  /// This only gets initialized if the base subobject type is
+  /// different from the complete-object type.
+  llvm::StructType *BaseSubobjectType;
+
+  /// FieldInfo - Holds a field and its corresponding LLVM field number.
+  llvm::DenseMap<const FieldDecl *, unsigned> Fields;
+
+  /// BitFieldInfo - Holds location and size information about a bit field.
+  llvm::DenseMap<const FieldDecl *, CGBitFieldInfo> BitFields;
+
+  llvm::DenseMap<const CXXRecordDecl *, unsigned> NonVirtualBases;
+  llvm::DenseMap<const CXXRecordDecl *, unsigned> VirtualBases;
+
+  /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
+  /// primary base classes for some other direct or indirect base class.
+  CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
+
+  /// LaidOutVirtualBases - A set of all laid out virtual bases, used to avoid
+  /// avoid laying out virtual bases more than once.
+  llvm::SmallPtrSet<const CXXRecordDecl *, 4> LaidOutVirtualBases;
+  
+  /// IsZeroInitializable - Whether this struct can be C++
+  /// zero-initialized with an LLVM zeroinitializer.
+  bool IsZeroInitializable;
+  bool IsZeroInitializableAsBase;
+
+  /// Packed - Whether the resulting LLVM struct will be packed or not.
+  bool Packed;
+  
+  /// IsMsStruct - Whether ms_struct is in effect or not
+  bool IsMsStruct;
+
+private:
+  CodeGenTypes &Types;
+
+  /// LastLaidOutBaseInfo - Contains the offset and non-virtual size of the
+  /// last base laid out. Used so that we can replace the last laid out base
+  /// type with an i8 array if needed.
+  struct LastLaidOutBaseInfo {
+    CharUnits Offset;
+    CharUnits NonVirtualSize;
+
+    bool isValid() const { return !NonVirtualSize.isZero(); }
+    void invalidate() { NonVirtualSize = CharUnits::Zero(); }
+  
+  } LastLaidOutBase;
+
+  /// Alignment - Contains the alignment of the RecordDecl.
+  CharUnits Alignment;
+
+  /// BitsAvailableInLastField - If a bit field spans only part of a LLVM field,
+  /// this will have the number of bits still available in the field.
+  char BitsAvailableInLastField;
+
+  /// NextFieldOffset - Holds the next field offset.
+  CharUnits NextFieldOffset;
+
+  /// LayoutUnionField - Will layout a field in an union and return the type
+  /// that the field will have.
+  llvm::Type *LayoutUnionField(const FieldDecl *Field,
+                               const ASTRecordLayout &Layout);
+  
+  /// LayoutUnion - Will layout a union RecordDecl.
+  void LayoutUnion(const RecordDecl *D);
+
+  /// LayoutField - try to layout all fields in the record decl.
+  /// Returns false if the operation failed because the struct is not packed.
+  bool LayoutFields(const RecordDecl *D);
+
+  /// Layout a single base, virtual or non-virtual
+  bool LayoutBase(const CXXRecordDecl *base,
+                  const CGRecordLayout &baseLayout,
+                  CharUnits baseOffset);
+
+  /// LayoutVirtualBase - layout a single virtual base.
+  bool LayoutVirtualBase(const CXXRecordDecl *base,
+                         CharUnits baseOffset);
+
+  /// LayoutVirtualBases - layout the virtual bases of a record decl.
+  bool LayoutVirtualBases(const CXXRecordDecl *RD,
+                          const ASTRecordLayout &Layout);
+
+  /// MSLayoutVirtualBases - layout the virtual bases of a record decl,
+  /// like MSVC.
+  bool MSLayoutVirtualBases(const CXXRecordDecl *RD,
+                            const ASTRecordLayout &Layout);
+  
+  /// LayoutNonVirtualBase - layout a single non-virtual base.
+  bool LayoutNonVirtualBase(const CXXRecordDecl *base,
+                            CharUnits baseOffset);
+  
+  /// LayoutNonVirtualBases - layout the virtual bases of a record decl.
+  bool LayoutNonVirtualBases(const CXXRecordDecl *RD, 
+                             const ASTRecordLayout &Layout);
+
+  /// ComputeNonVirtualBaseType - Compute the non-virtual base field types.
+  bool ComputeNonVirtualBaseType(const CXXRecordDecl *RD);
+  
+  /// LayoutField - layout a single field. Returns false if the operation failed
+  /// because the current struct is not packed.
+  bool LayoutField(const FieldDecl *D, uint64_t FieldOffset);
+
+  /// LayoutBitField - layout a single bit field.
+  void LayoutBitField(const FieldDecl *D, uint64_t FieldOffset);
+
+  /// AppendField - Appends a field with the given offset and type.
+  void AppendField(CharUnits fieldOffset, llvm::Type *FieldTy);
+
+  /// AppendPadding - Appends enough padding bytes so that the total
+  /// struct size is a multiple of the field alignment.
+  void AppendPadding(CharUnits fieldOffset, CharUnits fieldAlignment);
+
+  /// ResizeLastBaseFieldIfNecessary - Fields and bases can be laid out in the
+  /// tail padding of a previous base. If this happens, the type of the previous
+  /// base needs to be changed to an array of i8. Returns true if the last
+  /// laid out base was resized.
+  bool ResizeLastBaseFieldIfNecessary(CharUnits offset);
+
+  /// getByteArrayType - Returns a byte array type with the given number of
+  /// elements.
+  llvm::Type *getByteArrayType(CharUnits NumBytes);
+  
+  /// AppendBytes - Append a given number of bytes to the record.
+  void AppendBytes(CharUnits numBytes);
+
+  /// AppendTailPadding - Append enough tail padding so that the type will have
+  /// the passed size.
+  void AppendTailPadding(CharUnits RecordSize);
+
+  CharUnits getTypeAlignment(llvm::Type *Ty) const;
+
+  /// getAlignmentAsLLVMStruct - Returns the maximum alignment of all the
+  /// LLVM element types.
+  CharUnits getAlignmentAsLLVMStruct() const;
+
+  /// CheckZeroInitializable - Check if the given type contains a pointer
+  /// to data member.
+  void CheckZeroInitializable(QualType T);
+
+public:
+  CGRecordLayoutBuilder(CodeGenTypes &Types)
+    : BaseSubobjectType(0),
+      IsZeroInitializable(true), IsZeroInitializableAsBase(true),
+      Packed(false), IsMsStruct(false),
+      Types(Types), BitsAvailableInLastField(0) { }
+
+  /// Layout - Will layout a RecordDecl.
+  void Layout(const RecordDecl *D);
+};
+
+}
+
+void CGRecordLayoutBuilder::Layout(const RecordDecl *D) {
+  Alignment = Types.getContext().getASTRecordLayout(D).getAlignment();
+  Packed = D->hasAttr<PackedAttr>();
+  
+  IsMsStruct = D->hasAttr<MsStructAttr>();
+
+  if (D->isUnion()) {
+    LayoutUnion(D);
+    return;
+  }
+
+  if (LayoutFields(D))
+    return;
+
+  // We weren't able to layout the struct. Try again with a packed struct
+  Packed = true;
+  LastLaidOutBase.invalidate();
+  NextFieldOffset = CharUnits::Zero();
+  FieldTypes.clear();
+  Fields.clear();
+  BitFields.clear();
+  NonVirtualBases.clear();
+  VirtualBases.clear();
+
+  LayoutFields(D);
+}
+
+CGBitFieldInfo CGBitFieldInfo::MakeInfo(CodeGenTypes &Types,
+                               const FieldDecl *FD,
+                               uint64_t FieldOffset,
+                               uint64_t FieldSize,
+                               uint64_t ContainingTypeSizeInBits,
+                               unsigned ContainingTypeAlign) {
+  llvm::Type *Ty = Types.ConvertTypeForMem(FD->getType());
+  CharUnits TypeSizeInBytes =
+    CharUnits::fromQuantity(Types.getTargetData().getTypeAllocSize(Ty));
+  uint64_t TypeSizeInBits = Types.getContext().toBits(TypeSizeInBytes);
+
+  bool IsSigned = FD->getType()->isSignedIntegerOrEnumerationType();
+
+  if (FieldSize > TypeSizeInBits) {
+    // We have a wide bit-field. The extra bits are only used for padding, so
+    // if we have a bitfield of type T, with size N:
+    //
+    // T t : N;
+    //
+    // We can just assume that it's:
+    //
+    // T t : sizeof(T);
+    //
+    FieldSize = TypeSizeInBits;
+  }
+
+  // in big-endian machines the first fields are in higher bit positions,
+  // so revert the offset. The byte offsets are reversed(back) later.
+  if (Types.getTargetData().isBigEndian()) {
+    FieldOffset = ((ContainingTypeSizeInBits)-FieldOffset-FieldSize);
+  }
+
+  // Compute the access components. The policy we use is to start by attempting
+  // to access using the width of the bit-field type itself and to always access
+  // at aligned indices of that type. If such an access would fail because it
+  // extends past the bound of the type, then we reduce size to the next smaller
+  // power of two and retry. The current algorithm assumes pow2 sized types,
+  // although this is easy to fix.
+  //
+  assert(llvm::isPowerOf2_32(TypeSizeInBits) && "Unexpected type size!");
+  CGBitFieldInfo::AccessInfo Components[3];
+  unsigned NumComponents = 0;
+  unsigned AccessedTargetBits = 0;       // The number of target bits accessed.
+  unsigned AccessWidth = TypeSizeInBits; // The current access width to attempt.
+
+  // If requested, widen the initial bit-field access to be register sized. The
+  // theory is that this is most likely to allow multiple accesses into the same
+  // structure to be coalesced, and that the backend should be smart enough to
+  // narrow the store if no coalescing is ever done.
+  //
+  // The subsequent code will handle align these access to common boundaries and
+  // guaranteeing that we do not access past the end of the structure.
+  if (Types.getCodeGenOpts().UseRegisterSizedBitfieldAccess) {
+    if (AccessWidth < Types.getTarget().getRegisterWidth())
+      AccessWidth = Types.getTarget().getRegisterWidth();
+  }
+
+  // Round down from the field offset to find the first access position that is
+  // at an aligned offset of the initial access type.
+  uint64_t AccessStart = FieldOffset - (FieldOffset % AccessWidth);
+
+  // Adjust initial access size to fit within record.
+  while (AccessWidth > Types.getTarget().getCharWidth() &&
+         AccessStart + AccessWidth > ContainingTypeSizeInBits) {
+    AccessWidth >>= 1;
+    AccessStart = FieldOffset - (FieldOffset % AccessWidth);
+  }
+
+  while (AccessedTargetBits < FieldSize) {
+    // Check that we can access using a type of this size, without reading off
+    // the end of the structure. This can occur with packed structures and
+    // -fno-bitfield-type-align, for example.
+    if (AccessStart + AccessWidth > ContainingTypeSizeInBits) {
+      // If so, reduce access size to the next smaller power-of-two and retry.
+      AccessWidth >>= 1;
+      assert(AccessWidth >= Types.getTarget().getCharWidth()
+             && "Cannot access under byte size!");
+      continue;
+    }
+
+    // Otherwise, add an access component.
+
+    // First, compute the bits inside this access which are part of the
+    // target. We are reading bits [AccessStart, AccessStart + AccessWidth); the
+    // intersection with [FieldOffset, FieldOffset + FieldSize) gives the bits
+    // in the target that we are reading.
+    assert(FieldOffset < AccessStart + AccessWidth && "Invalid access start!");
+    assert(AccessStart < FieldOffset + FieldSize && "Invalid access start!");
+    uint64_t AccessBitsInFieldStart = std::max(AccessStart, FieldOffset);
+    uint64_t AccessBitsInFieldSize =
+      std::min(AccessWidth + AccessStart,
+               FieldOffset + FieldSize) - AccessBitsInFieldStart;
+
+    assert(NumComponents < 3 && "Unexpected number of components!");
+    CGBitFieldInfo::AccessInfo &AI = Components[NumComponents++];
+    AI.FieldIndex = 0;
+    // FIXME: We still follow the old access pattern of only using the field
+    // byte offset. We should switch this once we fix the struct layout to be
+    // pretty.
+
+    // on big-endian machines we reverted the bit offset because first fields are
+    // in higher bits. But this also reverts the bytes, so fix this here by reverting
+    // the byte offset on big-endian machines.
+    if (Types.getTargetData().isBigEndian()) {
+      AI.FieldByteOffset = Types.getContext().toCharUnitsFromBits(
+          ContainingTypeSizeInBits - AccessStart - AccessWidth);
+    } else {
+      AI.FieldByteOffset = Types.getContext().toCharUnitsFromBits(AccessStart);
+    }
+    AI.FieldBitStart = AccessBitsInFieldStart - AccessStart;
+    AI.AccessWidth = AccessWidth;
+    AI.AccessAlignment = Types.getContext().toCharUnitsFromBits(
+        llvm::MinAlign(ContainingTypeAlign, AccessStart));
+    AI.TargetBitOffset = AccessedTargetBits;
+    AI.TargetBitWidth = AccessBitsInFieldSize;
+
+    AccessStart += AccessWidth;
+    AccessedTargetBits += AI.TargetBitWidth;
+  }
+
+  assert(AccessedTargetBits == FieldSize && "Invalid bit-field access!");
+  return CGBitFieldInfo(FieldSize, NumComponents, Components, IsSigned);
+}
+
+CGBitFieldInfo CGBitFieldInfo::MakeInfo(CodeGenTypes &Types,
+                                        const FieldDecl *FD,
+                                        uint64_t FieldOffset,
+                                        uint64_t FieldSize) {
+  const RecordDecl *RD = FD->getParent();
+  const ASTRecordLayout &RL = Types.getContext().getASTRecordLayout(RD);
+  uint64_t ContainingTypeSizeInBits = Types.getContext().toBits(RL.getSize());
+  unsigned ContainingTypeAlign = Types.getContext().toBits(RL.getAlignment());
+
+  return MakeInfo(Types, FD, FieldOffset, FieldSize, ContainingTypeSizeInBits,
+                  ContainingTypeAlign);
+}
+
+void CGRecordLayoutBuilder::LayoutBitField(const FieldDecl *D,
+                                           uint64_t fieldOffset) {
+  uint64_t fieldSize = D->getBitWidthValue(Types.getContext());
+
+  if (fieldSize == 0)
+    return;
+
+  uint64_t nextFieldOffsetInBits = Types.getContext().toBits(NextFieldOffset);
+  CharUnits numBytesToAppend;
+  unsigned charAlign = Types.getContext().getTargetInfo().getCharAlign();
+
+  if (fieldOffset < nextFieldOffsetInBits && !BitsAvailableInLastField) {
+    assert(fieldOffset % charAlign == 0 && 
+           "Field offset not aligned correctly");
+
+    CharUnits fieldOffsetInCharUnits = 
+      Types.getContext().toCharUnitsFromBits(fieldOffset);
+
+    // Try to resize the last base field.
+    if (ResizeLastBaseFieldIfNecessary(fieldOffsetInCharUnits))
+      nextFieldOffsetInBits = Types.getContext().toBits(NextFieldOffset);
+  }
+
+  if (fieldOffset < nextFieldOffsetInBits) {
+    assert(BitsAvailableInLastField && "Bitfield size mismatch!");
+    assert(!NextFieldOffset.isZero() && "Must have laid out at least one byte");
+
+    // The bitfield begins in the previous bit-field.
+    numBytesToAppend = Types.getContext().toCharUnitsFromBits(
+      llvm::RoundUpToAlignment(fieldSize - BitsAvailableInLastField, 
+                               charAlign));
+  } else {
+    assert(fieldOffset % charAlign == 0 && 
+           "Field offset not aligned correctly");
+
+    // Append padding if necessary.
+    AppendPadding(Types.getContext().toCharUnitsFromBits(fieldOffset), 
+                  CharUnits::One());
+
+    numBytesToAppend = Types.getContext().toCharUnitsFromBits(
+        llvm::RoundUpToAlignment(fieldSize, charAlign));
+
+    assert(!numBytesToAppend.isZero() && "No bytes to append!");
+  }
+
+  // Add the bit field info.
+  BitFields.insert(std::make_pair(D,
+                   CGBitFieldInfo::MakeInfo(Types, D, fieldOffset, fieldSize)));
+
+  AppendBytes(numBytesToAppend);
+
+  BitsAvailableInLastField =
+    Types.getContext().toBits(NextFieldOffset) - (fieldOffset + fieldSize);
+}
+
+bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D,
+                                        uint64_t fieldOffset) {
+  // If the field is packed, then we need a packed struct.
+  if (!Packed && D->hasAttr<PackedAttr>())
+    return false;
+
+  if (D->isBitField()) {
+    // We must use packed structs for unnamed bit fields since they
+    // don't affect the struct alignment.
+    if (!Packed && !D->getDeclName())
+      return false;
+
+    LayoutBitField(D, fieldOffset);
+    return true;
+  }
+
+  CheckZeroInitializable(D->getType());
+
+  assert(fieldOffset % Types.getTarget().getCharWidth() == 0
+         && "field offset is not on a byte boundary!");
+  CharUnits fieldOffsetInBytes
+    = Types.getContext().toCharUnitsFromBits(fieldOffset);
+
+  llvm::Type *Ty = Types.ConvertTypeForMem(D->getType());
+  CharUnits typeAlignment = getTypeAlignment(Ty);
+
+  // If the type alignment is larger then the struct alignment, we must use
+  // a packed struct.
+  if (typeAlignment > Alignment) {
+    assert(!Packed && "Alignment is wrong even with packed struct!");
+    return false;
+  }
+
+  if (!Packed) {
+    if (const RecordType *RT = D->getType()->getAs<RecordType>()) {
+      const RecordDecl *RD = cast<RecordDecl>(RT->getDecl());
+      if (const MaxFieldAlignmentAttr *MFAA =
+            RD->getAttr<MaxFieldAlignmentAttr>()) {
+        if (MFAA->getAlignment() != Types.getContext().toBits(typeAlignment))
+          return false;
+      }
+    }
+  }
+
+  // Round up the field offset to the alignment of the field type.
+  CharUnits alignedNextFieldOffsetInBytes =
+    NextFieldOffset.RoundUpToAlignment(typeAlignment);
+
+  if (fieldOffsetInBytes < alignedNextFieldOffsetInBytes) {
+    // Try to resize the last base field.
+    if (ResizeLastBaseFieldIfNecessary(fieldOffsetInBytes)) {
+      alignedNextFieldOffsetInBytes = 
+        NextFieldOffset.RoundUpToAlignment(typeAlignment);
+    }
+  }
+
+  if (fieldOffsetInBytes < alignedNextFieldOffsetInBytes) {
+    assert(!Packed && "Could not place field even with packed struct!");
+    return false;
+  }
+
+  AppendPadding(fieldOffsetInBytes, typeAlignment);
+
+  // Now append the field.
+  Fields[D] = FieldTypes.size();
+  AppendField(fieldOffsetInBytes, Ty);
+
+  LastLaidOutBase.invalidate();
+  return true;
+}
+
+llvm::Type *
+CGRecordLayoutBuilder::LayoutUnionField(const FieldDecl *Field,
+                                        const ASTRecordLayout &Layout) {
+  if (Field->isBitField()) {
+    uint64_t FieldSize = Field->getBitWidthValue(Types.getContext());
+
+    // Ignore zero sized bit fields.
+    if (FieldSize == 0)
+      return 0;
+
+    llvm::Type *FieldTy = llvm::Type::getInt8Ty(Types.getLLVMContext());
+    CharUnits NumBytesToAppend = Types.getContext().toCharUnitsFromBits(
+      llvm::RoundUpToAlignment(FieldSize, 
+                               Types.getContext().getTargetInfo().getCharAlign()));
+
+    if (NumBytesToAppend > CharUnits::One())
+      FieldTy = llvm::ArrayType::get(FieldTy, NumBytesToAppend.getQuantity());
+
+    // Add the bit field info.
+    BitFields.insert(std::make_pair(Field,
+                         CGBitFieldInfo::MakeInfo(Types, Field, 0, FieldSize)));
+    return FieldTy;
+  }
+
+  // This is a regular union field.
+  Fields[Field] = 0;
+  return Types.ConvertTypeForMem(Field->getType());
+}
+
+void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) {
+  assert(D->isUnion() && "Can't call LayoutUnion on a non-union record!");
+
+  const ASTRecordLayout &layout = Types.getContext().getASTRecordLayout(D);
+
+  llvm::Type *unionType = 0;
+  CharUnits unionSize = CharUnits::Zero();
+  CharUnits unionAlign = CharUnits::Zero();
+
+  bool hasOnlyZeroSizedBitFields = true;
+  bool checkedFirstFieldZeroInit = false;
+
+  unsigned fieldNo = 0;
+  for (RecordDecl::field_iterator field = D->field_begin(),
+       fieldEnd = D->field_end(); field != fieldEnd; ++field, ++fieldNo) {
+    assert(layout.getFieldOffset(fieldNo) == 0 &&
+          "Union field offset did not start at the beginning of record!");
+    llvm::Type *fieldType = LayoutUnionField(*field, layout);
+
+    if (!fieldType)
+      continue;
+
+    if (field->getDeclName() && !checkedFirstFieldZeroInit) {
+      CheckZeroInitializable(field->getType());
+      checkedFirstFieldZeroInit = true;
+    }
+
+    hasOnlyZeroSizedBitFields = false;
+
+    CharUnits fieldAlign = CharUnits::fromQuantity(
+                          Types.getTargetData().getABITypeAlignment(fieldType));
+    CharUnits fieldSize = CharUnits::fromQuantity(
+                             Types.getTargetData().getTypeAllocSize(fieldType));
+
+    if (fieldAlign < unionAlign)
+      continue;
+
+    if (fieldAlign > unionAlign || fieldSize > unionSize) {
+      unionType = fieldType;
+      unionAlign = fieldAlign;
+      unionSize = fieldSize;
+    }
+  }
+
+  // Now add our field.
+  if (unionType) {
+    AppendField(CharUnits::Zero(), unionType);
+
+    if (getTypeAlignment(unionType) > layout.getAlignment()) {
+      // We need a packed struct.
+      Packed = true;
+      unionAlign = CharUnits::One();
+    }
+  }
+  if (unionAlign.isZero()) {
+    (void)hasOnlyZeroSizedBitFields;
+    assert(hasOnlyZeroSizedBitFields &&
+           "0-align record did not have all zero-sized bit-fields!");
+    unionAlign = CharUnits::One();
+  }
+
+  // Append tail padding.
+  CharUnits recordSize = layout.getSize();
+  if (recordSize > unionSize)
+    AppendPadding(recordSize, unionAlign);
+}
+
+bool CGRecordLayoutBuilder::LayoutBase(const CXXRecordDecl *base,
+                                       const CGRecordLayout &baseLayout,
+                                       CharUnits baseOffset) {
+  ResizeLastBaseFieldIfNecessary(baseOffset);
+
+  AppendPadding(baseOffset, CharUnits::One());
+
+  const ASTRecordLayout &baseASTLayout
+    = Types.getContext().getASTRecordLayout(base);
+
+  LastLaidOutBase.Offset = NextFieldOffset;
+  LastLaidOutBase.NonVirtualSize = baseASTLayout.getNonVirtualSize();
+
+  llvm::StructType *subobjectType = baseLayout.getBaseSubobjectLLVMType();
+  if (getTypeAlignment(subobjectType) > Alignment)
+    return false;
+
+  AppendField(baseOffset, subobjectType);
+  return true;
+}
+
+bool CGRecordLayoutBuilder::LayoutNonVirtualBase(const CXXRecordDecl *base,
+                                                 CharUnits baseOffset) {
+  // Ignore empty bases.
+  if (base->isEmpty()) return true;
+
+  const CGRecordLayout &baseLayout = Types.getCGRecordLayout(base);
+  if (IsZeroInitializableAsBase) {
+    assert(IsZeroInitializable &&
+           "class zero-initializable as base but not as complete object");
+
+    IsZeroInitializable = IsZeroInitializableAsBase =
+      baseLayout.isZeroInitializableAsBase();
+  }
+
+  if (!LayoutBase(base, baseLayout, baseOffset))
+    return false;
+  NonVirtualBases[base] = (FieldTypes.size() - 1);
+  return true;
+}
+
+bool
+CGRecordLayoutBuilder::LayoutVirtualBase(const CXXRecordDecl *base,
+                                         CharUnits baseOffset) {
+  // Ignore empty bases.
+  if (base->isEmpty()) return true;
+
+  const CGRecordLayout &baseLayout = Types.getCGRecordLayout(base);
+  if (IsZeroInitializable)
+    IsZeroInitializable = baseLayout.isZeroInitializableAsBase();
+
+  if (!LayoutBase(base, baseLayout, baseOffset))
+    return false;
+  VirtualBases[base] = (FieldTypes.size() - 1);
+  return true;
+}
+
+bool
+CGRecordLayoutBuilder::MSLayoutVirtualBases(const CXXRecordDecl *RD,
+                                          const ASTRecordLayout &Layout) {
+  if (!RD->getNumVBases())
+    return true;
+
+  // The vbases list is uniqued and ordered by a depth-first
+  // traversal, which is what we need here.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
+        E = RD->vbases_end(); I != E; ++I) {
+
+    const CXXRecordDecl *BaseDecl = 
+      cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
+
+    CharUnits vbaseOffset = Layout.getVBaseClassOffset(BaseDecl);
+    if (!LayoutVirtualBase(BaseDecl, vbaseOffset))
+      return false;
+  }
+  return true;
+}
+
+/// LayoutVirtualBases - layout the non-virtual bases of a record decl.
+bool
+CGRecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
+                                          const ASTRecordLayout &Layout) {
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+       E = RD->bases_end(); I != E; ++I) {
+    const CXXRecordDecl *BaseDecl = 
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    // We only want to lay out virtual bases that aren't indirect primary bases
+    // of some other base.
+    if (I->isVirtual() && !IndirectPrimaryBases.count(BaseDecl)) {
+      // Only lay out the base once.
+      if (!LaidOutVirtualBases.insert(BaseDecl))
+        continue;
+
+      CharUnits vbaseOffset = Layout.getVBaseClassOffset(BaseDecl);
+      if (!LayoutVirtualBase(BaseDecl, vbaseOffset))
+        return false;
+    }
+
+    if (!BaseDecl->getNumVBases()) {
+      // This base isn't interesting since it doesn't have any virtual bases.
+      continue;
+    }
+    
+    if (!LayoutVirtualBases(BaseDecl, Layout))
+      return false;
+  }
+  return true;
+}
+
+bool
+CGRecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD,
+                                             const ASTRecordLayout &Layout) {
+  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
+
+  // If we have a primary base, lay it out first.
+  if (PrimaryBase) {
+    if (!Layout.isPrimaryBaseVirtual()) {
+      if (!LayoutNonVirtualBase(PrimaryBase, CharUnits::Zero()))
+        return false;
+    } else {
+      if (!LayoutVirtualBase(PrimaryBase, CharUnits::Zero()))
+        return false;
+    }
+
+  // Otherwise, add a vtable / vf-table if the layout says to do so.
+  } else if (Types.getContext().getTargetInfo().getCXXABI() == CXXABI_Microsoft
+               ? Layout.getVFPtrOffset() != CharUnits::fromQuantity(-1)
+               : RD->isDynamicClass()) {
+    llvm::Type *FunctionType =
+      llvm::FunctionType::get(llvm::Type::getInt32Ty(Types.getLLVMContext()),
+                              /*isVarArg=*/true);
+    llvm::Type *VTableTy = FunctionType->getPointerTo();
+    
+    assert(NextFieldOffset.isZero() &&
+           "VTable pointer must come first!");
+    AppendField(CharUnits::Zero(), VTableTy->getPointerTo());
+  }
+
+  // Layout the non-virtual bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+       E = RD->bases_end(); I != E; ++I) {
+    if (I->isVirtual())
+      continue;
+
+    const CXXRecordDecl *BaseDecl = 
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    // We've already laid out the primary base.
+    if (BaseDecl == PrimaryBase && !Layout.isPrimaryBaseVirtual())
+      continue;
+
+    if (!LayoutNonVirtualBase(BaseDecl, Layout.getBaseClassOffset(BaseDecl)))
+      return false;
+  }
+
+  // Add a vb-table pointer if the layout insists.
+  if (Layout.getVBPtrOffset() != CharUnits::fromQuantity(-1)) {
+    CharUnits VBPtrOffset = Layout.getVBPtrOffset();
+    llvm::Type *Vbptr = llvm::Type::getInt32PtrTy(Types.getLLVMContext());
+    AppendPadding(VBPtrOffset, getTypeAlignment(Vbptr));
+    AppendField(VBPtrOffset, Vbptr);
+  }
+
+  return true;
+}
+
+bool
+CGRecordLayoutBuilder::ComputeNonVirtualBaseType(const CXXRecordDecl *RD) {
+  const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(RD);
+
+  CharUnits NonVirtualSize  = Layout.getNonVirtualSize();
+  CharUnits NonVirtualAlign = Layout.getNonVirtualAlign();
+  CharUnits AlignedNonVirtualTypeSize =
+    NonVirtualSize.RoundUpToAlignment(NonVirtualAlign);
+  
+  // First check if we can use the same fields as for the complete class.
+  CharUnits RecordSize = Layout.getSize();
+  if (AlignedNonVirtualTypeSize == RecordSize)
+    return true;
+
+  // Check if we need padding.
+  CharUnits AlignedNextFieldOffset =
+    NextFieldOffset.RoundUpToAlignment(getAlignmentAsLLVMStruct());
+
+  if (AlignedNextFieldOffset > AlignedNonVirtualTypeSize) {
+    assert(!Packed && "cannot layout even as packed struct");
+    return false; // Needs packing.
+  }
+
+  bool needsPadding = (AlignedNonVirtualTypeSize != AlignedNextFieldOffset);
+  if (needsPadding) {
+    CharUnits NumBytes = AlignedNonVirtualTypeSize - AlignedNextFieldOffset;
+    FieldTypes.push_back(getByteArrayType(NumBytes));
+  }
+  
+  BaseSubobjectType = llvm::StructType::create(Types.getLLVMContext(),
+                                               FieldTypes, "", Packed);
+  Types.addRecordTypeName(RD, BaseSubobjectType, ".base");
+
+  // Pull the padding back off.
+  if (needsPadding)
+    FieldTypes.pop_back();
+
+  return true;
+}
+
+bool CGRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
+  assert(!D->isUnion() && "Can't call LayoutFields on a union!");
+  assert(!Alignment.isZero() && "Did not set alignment!");
+
+  const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D);
+
+  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D);
+  if (RD)
+    if (!LayoutNonVirtualBases(RD, Layout))
+      return false;
+
+  unsigned FieldNo = 0;
+  const FieldDecl *LastFD = 0;
+  
+  for (RecordDecl::field_iterator Field = D->field_begin(),
+       FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
+    if (IsMsStruct) {
+      // Zero-length bitfields following non-bitfield members are
+      // ignored:
+      const FieldDecl *FD =  (*Field);
+      if (Types.getContext().ZeroBitfieldFollowsNonBitfield(FD, LastFD)) {
+        --FieldNo;
+        continue;
+      }
+      LastFD = FD;
+    }
+    
+    if (!LayoutField(*Field, Layout.getFieldOffset(FieldNo))) {
+      assert(!Packed &&
+             "Could not layout fields even with a packed LLVM struct!");
+      return false;
+    }
+  }
+
+  if (RD) {
+    // We've laid out the non-virtual bases and the fields, now compute the
+    // non-virtual base field types.
+    if (!ComputeNonVirtualBaseType(RD)) {
+      assert(!Packed && "Could not layout even with a packed LLVM struct!");
+      return false;
+    }
+
+    // Lay out the virtual bases.  The MS ABI uses a different
+    // algorithm here due to the lack of primary virtual bases.
+    if (Types.getContext().getTargetInfo().getCXXABI() != CXXABI_Microsoft) {
+      RD->getIndirectPrimaryBases(IndirectPrimaryBases);
+      if (Layout.isPrimaryBaseVirtual())
+        IndirectPrimaryBases.insert(Layout.getPrimaryBase());
+
+      if (!LayoutVirtualBases(RD, Layout))
+        return false;
+    } else {
+      if (!MSLayoutVirtualBases(RD, Layout))
+        return false;
+    }
+  }
+  
+  // Append tail padding if necessary.
+  AppendTailPadding(Layout.getSize());
+
+  return true;
+}
+
+void CGRecordLayoutBuilder::AppendTailPadding(CharUnits RecordSize) {
+  ResizeLastBaseFieldIfNecessary(RecordSize);
+
+  assert(NextFieldOffset <= RecordSize && "Size mismatch!");
+
+  CharUnits AlignedNextFieldOffset =
+    NextFieldOffset.RoundUpToAlignment(getAlignmentAsLLVMStruct());
+
+  if (AlignedNextFieldOffset == RecordSize) {
+    // We don't need any padding.
+    return;
+  }
+
+  CharUnits NumPadBytes = RecordSize - NextFieldOffset;
+  AppendBytes(NumPadBytes);
+}
+
+void CGRecordLayoutBuilder::AppendField(CharUnits fieldOffset,
+                                        llvm::Type *fieldType) {
+  CharUnits fieldSize =
+    CharUnits::fromQuantity(Types.getTargetData().getTypeAllocSize(fieldType));
+
+  FieldTypes.push_back(fieldType);
+
+  NextFieldOffset = fieldOffset + fieldSize;
+  BitsAvailableInLastField = 0;
+}
+
+void CGRecordLayoutBuilder::AppendPadding(CharUnits fieldOffset,
+                                          CharUnits fieldAlignment) {
+  assert(NextFieldOffset <= fieldOffset &&
+         "Incorrect field layout!");
+
+  // Do nothing if we're already at the right offset.
+  if (fieldOffset == NextFieldOffset) return;
+
+  // If we're not emitting a packed LLVM type, try to avoid adding
+  // unnecessary padding fields.
+  if (!Packed) {
+    // Round up the field offset to the alignment of the field type.
+    CharUnits alignedNextFieldOffset =
+      NextFieldOffset.RoundUpToAlignment(fieldAlignment);
+    assert(alignedNextFieldOffset <= fieldOffset);
+
+    // If that's the right offset, we're done.
+    if (alignedNextFieldOffset == fieldOffset) return;
+  }
+
+  // Otherwise we need explicit padding.
+  CharUnits padding = fieldOffset - NextFieldOffset;
+  AppendBytes(padding);
+}
+
+bool CGRecordLayoutBuilder::ResizeLastBaseFieldIfNecessary(CharUnits offset) {
+  // Check if we have a base to resize.
+  if (!LastLaidOutBase.isValid())
+    return false;
+
+  // This offset does not overlap with the tail padding.
+  if (offset >= NextFieldOffset)
+    return false;
+
+  // Restore the field offset and append an i8 array instead.
+  FieldTypes.pop_back();
+  NextFieldOffset = LastLaidOutBase.Offset;
+  AppendBytes(LastLaidOutBase.NonVirtualSize);
+  LastLaidOutBase.invalidate();
+
+  return true;
+}
+
+llvm::Type *CGRecordLayoutBuilder::getByteArrayType(CharUnits numBytes) {
+  assert(!numBytes.isZero() && "Empty byte arrays aren't allowed.");
+
+  llvm::Type *Ty = llvm::Type::getInt8Ty(Types.getLLVMContext());
+  if (numBytes > CharUnits::One())
+    Ty = llvm::ArrayType::get(Ty, numBytes.getQuantity());
+
+  return Ty;
+}
+
+void CGRecordLayoutBuilder::AppendBytes(CharUnits numBytes) {
+  if (numBytes.isZero())
+    return;
+
+  // Append the padding field
+  AppendField(NextFieldOffset, getByteArrayType(numBytes));
+}
+
+CharUnits CGRecordLayoutBuilder::getTypeAlignment(llvm::Type *Ty) const {
+  if (Packed)
+    return CharUnits::One();
+
+  return CharUnits::fromQuantity(Types.getTargetData().getABITypeAlignment(Ty));
+}
+
+CharUnits CGRecordLayoutBuilder::getAlignmentAsLLVMStruct() const {
+  if (Packed)
+    return CharUnits::One();
+
+  CharUnits maxAlignment = CharUnits::One();
+  for (size_t i = 0; i != FieldTypes.size(); ++i)
+    maxAlignment = std::max(maxAlignment, getTypeAlignment(FieldTypes[i]));
+
+  return maxAlignment;
+}
+
+/// Merge in whether a field of the given type is zero-initializable.
+void CGRecordLayoutBuilder::CheckZeroInitializable(QualType T) {
+  // This record already contains a member pointer.
+  if (!IsZeroInitializableAsBase)
+    return;
+
+  // Can only have member pointers if we're compiling C++.
+  if (!Types.getContext().getLangOpts().CPlusPlus)
+    return;
+
+  const Type *elementType = T->getBaseElementTypeUnsafe();
+
+  if (const MemberPointerType *MPT = elementType->getAs<MemberPointerType>()) {
+    if (!Types.getCXXABI().isZeroInitializable(MPT))
+      IsZeroInitializable = IsZeroInitializableAsBase = false;
+  } else if (const RecordType *RT = elementType->getAs<RecordType>()) {
+    const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
+    const CGRecordLayout &Layout = Types.getCGRecordLayout(RD);
+    if (!Layout.isZeroInitializable())
+      IsZeroInitializable = IsZeroInitializableAsBase = false;
+  }
+}
+
+CGRecordLayout *CodeGenTypes::ComputeRecordLayout(const RecordDecl *D,
+                                                  llvm::StructType *Ty) {
+  CGRecordLayoutBuilder Builder(*this);
+
+  Builder.Layout(D);
+
+  Ty->setBody(Builder.FieldTypes, Builder.Packed);
+
+  // If we're in C++, compute the base subobject type.
+  llvm::StructType *BaseTy = 0;
+  if (isa<CXXRecordDecl>(D) && !D->isUnion()) {
+    BaseTy = Builder.BaseSubobjectType;
+    if (!BaseTy) BaseTy = Ty;
+  }
+
+  CGRecordLayout *RL =
+    new CGRecordLayout(Ty, BaseTy, Builder.IsZeroInitializable,
+                       Builder.IsZeroInitializableAsBase);
+
+  RL->NonVirtualBases.swap(Builder.NonVirtualBases);
+  RL->CompleteObjectVirtualBases.swap(Builder.VirtualBases);
+
+  // Add all the field numbers.
+  RL->FieldInfo.swap(Builder.Fields);
+
+  // Add bitfield info.
+  RL->BitFields.swap(Builder.BitFields);
+
+  // Dump the layout, if requested.
+  if (getContext().getLangOpts().DumpRecordLayouts) {
+    llvm::errs() << "\n*** Dumping IRgen Record Layout\n";
+    llvm::errs() << "Record: ";
+    D->dump();
+    llvm::errs() << "\nLayout: ";
+    RL->dump();
+  }
+
+#ifndef NDEBUG
+  // Verify that the computed LLVM struct size matches the AST layout size.
+  const ASTRecordLayout &Layout = getContext().getASTRecordLayout(D);
+
+  uint64_t TypeSizeInBits = getContext().toBits(Layout.getSize());
+  assert(TypeSizeInBits == getTargetData().getTypeAllocSizeInBits(Ty) &&
+         "Type size mismatch!");
+
+  if (BaseTy) {
+    CharUnits NonVirtualSize  = Layout.getNonVirtualSize();
+    CharUnits NonVirtualAlign = Layout.getNonVirtualAlign();
+    CharUnits AlignedNonVirtualTypeSize = 
+      NonVirtualSize.RoundUpToAlignment(NonVirtualAlign);
+
+    uint64_t AlignedNonVirtualTypeSizeInBits = 
+      getContext().toBits(AlignedNonVirtualTypeSize);
+
+    assert(AlignedNonVirtualTypeSizeInBits == 
+           getTargetData().getTypeAllocSizeInBits(BaseTy) &&
+           "Type size mismatch!");
+  }
+                                     
+  // Verify that the LLVM and AST field offsets agree.
+  llvm::StructType *ST =
+    dyn_cast<llvm::StructType>(RL->getLLVMType());
+  const llvm::StructLayout *SL = getTargetData().getStructLayout(ST);
+
+  const ASTRecordLayout &AST_RL = getContext().getASTRecordLayout(D);
+  RecordDecl::field_iterator it = D->field_begin();
+  const FieldDecl *LastFD = 0;
+  bool IsMsStruct = D->hasAttr<MsStructAttr>();
+  for (unsigned i = 0, e = AST_RL.getFieldCount(); i != e; ++i, ++it) {
+    const FieldDecl *FD = *it;
+
+    // For non-bit-fields, just check that the LLVM struct offset matches the
+    // AST offset.
+    if (!FD->isBitField()) {
+      unsigned FieldNo = RL->getLLVMFieldNo(FD);
+      assert(AST_RL.getFieldOffset(i) == SL->getElementOffsetInBits(FieldNo) &&
+             "Invalid field offset!");
+      LastFD = FD;
+      continue;
+    }
+
+    if (IsMsStruct) {
+      // Zero-length bitfields following non-bitfield members are
+      // ignored:
+      if (getContext().ZeroBitfieldFollowsNonBitfield(FD, LastFD)) {
+        --i;
+        continue;
+      }
+      LastFD = FD;
+    }
+    
+    // Ignore unnamed bit-fields.
+    if (!FD->getDeclName()) {
+      LastFD = FD;
+      continue;
+    }
+    
+    const CGBitFieldInfo &Info = RL->getBitFieldInfo(FD);
+    for (unsigned i = 0, e = Info.getNumComponents(); i != e; ++i) {
+      const CGBitFieldInfo::AccessInfo &AI = Info.getComponent(i);
+
+      // Verify that every component access is within the structure.
+      uint64_t FieldOffset = SL->getElementOffsetInBits(AI.FieldIndex);
+      uint64_t AccessBitOffset = FieldOffset +
+        getContext().toBits(AI.FieldByteOffset);
+      assert(AccessBitOffset + AI.AccessWidth <= TypeSizeInBits &&
+             "Invalid bit-field access (out of range)!");
+    }
+  }
+#endif
+
+  return RL;
+}
+
+void CGRecordLayout::print(raw_ostream &OS) const {
+  OS << "<CGRecordLayout\n";
+  OS << "  LLVMType:" << *CompleteObjectType << "\n";
+  if (BaseSubobjectType)
+    OS << "  NonVirtualBaseLLVMType:" << *BaseSubobjectType << "\n"; 
+  OS << "  IsZeroInitializable:" << IsZeroInitializable << "\n";
+  OS << "  BitFields:[\n";
+
+  // Print bit-field infos in declaration order.
+  std::vector<std::pair<unsigned, const CGBitFieldInfo*> > BFIs;
+  for (llvm::DenseMap<const FieldDecl*, CGBitFieldInfo>::const_iterator
+         it = BitFields.begin(), ie = BitFields.end();
+       it != ie; ++it) {
+    const RecordDecl *RD = it->first->getParent();
+    unsigned Index = 0;
+    for (RecordDecl::field_iterator
+           it2 = RD->field_begin(); *it2 != it->first; ++it2)
+      ++Index;
+    BFIs.push_back(std::make_pair(Index, &it->second));
+  }
+  llvm::array_pod_sort(BFIs.begin(), BFIs.end());
+  for (unsigned i = 0, e = BFIs.size(); i != e; ++i) {
+    OS.indent(4);
+    BFIs[i].second->print(OS);
+    OS << "\n";
+  }
+
+  OS << "]>\n";
+}
+
+void CGRecordLayout::dump() const {
+  print(llvm::errs());
+}
+
+void CGBitFieldInfo::print(raw_ostream &OS) const {
+  OS << "<CGBitFieldInfo";
+  OS << " Size:" << Size;
+  OS << " IsSigned:" << IsSigned << "\n";
+
+  OS.indent(4 + strlen("<CGBitFieldInfo"));
+  OS << " NumComponents:" << getNumComponents();
+  OS << " Components: [";
+  if (getNumComponents()) {
+    OS << "\n";
+    for (unsigned i = 0, e = getNumComponents(); i != e; ++i) {
+      const AccessInfo &AI = getComponent(i);
+      OS.indent(8);
+      OS << "<AccessInfo"
+         << " FieldIndex:" << AI.FieldIndex
+         << " FieldByteOffset:" << AI.FieldByteOffset.getQuantity()
+         << " FieldBitStart:" << AI.FieldBitStart
+         << " AccessWidth:" << AI.AccessWidth << "\n";
+      OS.indent(8 + strlen("<AccessInfo"));
+      OS << " AccessAlignment:" << AI.AccessAlignment.getQuantity()
+         << " TargetBitOffset:" << AI.TargetBitOffset
+         << " TargetBitWidth:" << AI.TargetBitWidth
+         << ">\n";
+    }
+    OS.indent(4);
+  }
+  OS << "]>";
+}
+
+void CGBitFieldInfo::dump() const {
+  print(llvm::errs());
+}